Laser-Enhanced Passive Voltage Contrast for SOI Defect Detection
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Solution Overview
Problem
The existing passive voltage contrast (PVC) method is not applicable to electrically-floating integrated circuits (ICs) like those on SOI substrates without extensive and costly pre-processing, which involves grounding the body of the SOI device.
Innovation Solution
Incorporating a laser source into a Scanning Electron Microscope (SEM) system to enhance electron collection and contrast by inducing a photovoltaic effect, allowing for defect detection without the need for electrical grounding of the SOI device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If extensive pre-processing is performed to ground the body of SOI device, then PVC analysis can be applied to SOI devices, but the process becomes time consuming and expensive
Solution Approach 1:
The patent introduces a conductive adhesive layer as an intermediary substance between the SOI device body and the substrate. This adhesive layer provides a conductive pathway that grounds the electrically isolated body without requiring complex mechanical grinding and etching processes, thus eliminating the time-consuming pre-processing steps while enabling PVC analysis on SOI devices
Solution Approach 2:
The patent replaces the mechanical pre-processing system (which involves removing metallization layers, grinding through substrate, and etching insulator layers) with a simpler chemical bonding approach using conductive adhesive. This substitution eliminates the need for extensive mechanical processing while achieving the same goal of electrical grounding for PVC analysis
2Adaptability or versatility
If extensive pre-processing is performed to ground the body of SOI device, then PVC analysis can be applied to SOI devices, but the cost increases
Solution Approach 1:
The conductive adhesive layer serves as a cost-effective intermediary that provides electrical grounding without requiring expensive equipment and processes such as mechanical grinding, precision etching, and cleanroom operations. This simple chemical bonding approach significantly reduces manufacturing costs while enabling PVC analysis on SOI devices
Solution Approach 2:
The patent employs a disposable conductive adhesive layer that can be easily applied and removed without requiring expensive, complex, or permanent modifications to the SOI device structure. This approach uses inexpensive materials and processes compared to the alternative of mechanical grinding and etching
3Measurement precision
If laser signal is added to enhance electron collection, then contrast between defect site and surroundings increases, but the system complexity increases
Solution Approach 1:
The patent integrates the laser signal generation capability into the existing SEM system, allowing the same platform to perform both electron beam imaging and laser-enhanced imaging. This multi-functionality approach increases measurement precision through enhanced contrast while minimizing additional system complexity by reusing existing infrastructure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves image contrast and enables defect detection on SOI devices without pre-processing, enhancing the PVC capability and facilitating defect localization with better-defined features in images.
Implementation Method 1
a laser source which is structured to emit a laser signal toward the stage, at a same area as the e-beam
Data Source
AI summary
The present disclosure relates to a detection system, and, more particularly, to system for detection of passive voltage contrast and methods of use. The system includes a chamber; a stage provided within the chamber, configured to stage a target structure; an electron beam apparatus which is structured to emit an e-beam toward the stage; and a laser source which emits a laser signal toward the stage, at a same area as the e-beam.